The Koran comprises all of the recorded speeches and sayings of the prophet Mohammed and it has for nearly fifteen centuries been the absolute law and gospel of the Mohammedan religion. The teachings and revelations which are contained in it are believed by Mohammedans to have proceeded directly from God. They were delivered orally by Mohammed from time to time in the presence of his followers and until after the prophet's death in 632 no attempt was made to put them in organized written form. Many of the disciples, however, remembered the words their master had uttered, at least until they could inscribe them on palm leaves, bits of wood, bleached bones, or other such articles as happened to be at hand. In the reign of Abu-Bekr (632-634), Mohammed's successor, it became apparent that unless some measure was adopted to bring these scattered sayings together they were in a fair way to be lost for all time to come. Hence the caliph intrusted to a certain young man by the name of Zaid the task of collecting and putting in some sort of system all the teachings that had survived, whether in written form or merely in the minds of men. Zaid had served Mohammed in a capacity which we should designate perhaps as that of secretary, and so should have been well qualified for the work. In later years (about 660) the Koran, or "the reading," as the collection began to be called, was again thoroughly revised. Thereafter all older copies were destroyed and no farther changes in any respect were ever made.